1. Field of the Invention
The present invention relates to a reading apparatus configured to read a sheet for example an original represented by an auto document feeder unit (hereinafter referred to as ADF).
2. Description of the Related Art
A configuration in which reading units (image sensors) arranged respectively at positions in an original conveyance path opposing a front surface and a back surface of an original in order to read both surfaces (the front surface and the back surface) of the original automatically by the image reading apparatus as described above is generally known. However, in this configuration, reading sensors for the front surface and the back surface of the original need to be provided, and cost increases may result.
Accordingly, in Japanese Patent Laid-Open No. 10-126567, the reading unit is configured to be capable of moving in a main body of an apparatus so as to be capable of reading the originals in a plurality of conveyance paths by a single reading sensor.
Japanese Patent Laid-Open No. 6-30257 describes providing a reference portion as a white reference plate at a position facing the reading unit with the conveyance path of the original interposed therebetween for reading the original accurately, and correcting information read by the reading unit such as shading correction by sensing the provided reference portion.
However, in a configuration in which the reading unit moves such as that disclosed in Japanese Patent Laid-Open No. 10-126567, how the reference portion is arranged is not disclosed.
In the configuration in which the reference portion is arranged on the conveyance path as in Japanese Patent Laid-Open No. 6-30257, there is a case where the original comes into contact with the reference portion and hence foreign substances such as paper dust adhere to the reference portion or the reference portion is scratched by the original, so that the state of the reference portion may be changed by being scrubbed and hence damaged by the original when the original passes through the position facing the reading unit. In this manner, due to soiling or scratches of the reference portion, adequate correction relating to information read by the reading unit may not be performed.